The present disclosure relates to methods and systems for use in subterranean operations. More particularly, the present disclosure relates to methods and systems of using treatment chemicals in a wellbore.
Hydrolytically degradable polymers (generally aliphatic polyesters) have been used in a variety of applications in the oil field, such as fluid diversion, fluid-loss control, and filter-cake-removal applications. In general, diverting agents and fluid-loss-control materials are intended to function for a finite amount of time.
Generally, diversion operations are used to distribute treatment fluid uniformly over all of the treated zones, which can become difficult as the permeability contrast between treated zones increases. Examples of treatment fluids include acids, scale inhibitors, or fracturing fluids. A number of particulate diverting agents have been used commercially in diverting fluids. Examples of such materials include cellophane flakes, naphthalenes, crushed limestone, sodium tetraborate, oyster shells, gilsonite, paraformaldehyde, and rock salt. The removal of diverting agents after completion of an operation has, for example, included dissolving the particulate diverting agent with a secondary treatment fluid.
Recently, aliphatic polyester-based diverting agents have been used based on their ability to self-degrade in any aqueous fluid, whether acidic, neutral, or basic. These diverting agents can be produced in a variety of shapes, such as granules or flakes, and are considered environmentally benign, where flowback fluids containing degraded byproducts are nontoxic. For example, polylactic acid (PLA), a degradable polymer with increasing use as a diverting agent, through hydrolytic degradation produces lactic acid, which occurs naturally in the human body.
Degradation accelerators are generally used to aid degrading the diverting agent into corresponding benign byproducts. However, these degradation accelerators are typically liquids and/or water soluble. As a result, degradation accelerator treatments must be pumped as a separate treatment fluid stream after completing a diversion operation, can require additional equipment, time, and/or other resources that add complexity and decrease operation efficiency.
Illustrative embodiments of the present disclosure are described in detail herein. In the interest of clarity, not all features of an actual implementation may be described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions may be made to achieve the specific implementation goals, which may vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure.